An Alphamid of ~X~ lighter fabric would be my guess too. Dr Jordan seems to be using these a lot this winter. However I'm not sold on the way the door creates a vertical/flat side when closed up -- kind of like a sail. I'd prefer something more like a 'mini-mid' (pyramid shaped, a la Megamid, but 1+ person). But yeah, I'll be watching this one too.

He's still using a bivy with it tho'. Just wondering... is that necessary? I've stuck with the SpinnShelter all along because I don't feel the need to use a bivy with it... and a SpinnShelter minus bivy is still lighter (about about the same) as a tarp plus bivy. What I'd LOVE to see is the SpinnShelter made from this new nano fabric.

Why use a bivy in a shelter like the one pictured? Possible reasons include:

1. want to pitch it up a bit for ventilation and to minimize condensation. it's raining or rain is expected during the night, plus it's windy and don't want any wind driven spray/rain to soak a down sleeping bag.

2. have the shelter sealed up pretty tight under conditions that will likely form sufficient condensation on the underside of the single wall tarptent. don't want this dripping onto, or otherwise coming into contact with the bag should one move about or sit up.

perhaps there may not be much opportunity to dry the bag in the sun during the coming few days of the trek of the additional moisture accumulated from #'s 1 and 2 above?

just a thought. what am i missing either by omission, or by way of mistake in my reasons?

I suspect Paul's right on. The shelter footprint is pretty small and when pitched with an air gap at ground level (typical) rain spray and spindrift will certainly come inside (although much less than with a very small tarp). There will also be splash from dripping water. (Since bigger teepee shelters allow sleeping farther from the walls, less moisture will directly strike the bag.)

Also, a bivy will increase any sleeping system's warmth and I'll guess it was included for that reason as well. Ryan's always skating on the thin ice with his gear, and it looks pretty cold there :-)

I have been looking for a good design for a one man tent for winter use. Several years ago I made one but it was before Cuben and it weighed more than I wanted to carry. The new and coming soon maybe 7.5oz version of the Oware Alphamid looks like it might be a good design to try.

Last year, I think, Ryan and crew did a winter ski/hike and he used an Alphamid Tarp. I went to the Oware web site to check the size they come in to see what size the Alphamid Nano might be. The Oware product comes in a small at 4.5'x9'x 5.5' and one a little larger. I am sure Ryan would not go for the bigger model so I will guess the Alp..Nano might be the smaller size. I made a scale paper model to check the size and do a few "what-if's" for 4 different sizes. I wanted to see if a smaller size could be made in the 7.5oz range without Cuben/Nano fabric. I have decided I don't think so.

1. I first worked up the sq yards of the small size Oware Al.. (4.5'x9'x5.5') and got 10 sq yards plus or minus a little. [NOTE: I did not add any material for seams etc on any of the calculations.] 2. I worked up the sq yards for 4'x8'x5.5' and got 8.9 sq yards.3. I worked up the sq yards for 4'x7'x5.5 and got 8.15sq yards.4. I worked up the sq yards for 3.4'x7'x5.5' and got 7.78 sq yards.

My guess is that the Alphamid Nano is made out of something in the .50oz per sq yard range. Cuben - Nano what ever. The common weight of easy to get Cuben is in the 0.35 to 0.44 or so weight range. If you do the math it would seem that the 7.5oz weight number could be a little lower. It looks like it has a long zipper on the door part and that might add some of the extra weight.

The Cuben at .35 oz a sq yard and making the smallest size I worked up would take less than 3oz of fabric and the largest size of 4.5'x9'x5.5' would take 3.5oz of Cuben Fiber.

So the good news is we may see a new and very light weight 3.5 to 4 season Alphamid Nano Tarp at 7.5oz. The bad news is that 9 or 10 yards of Cuben/Nano fiber to make it that light will also cause it to cost ??? a bunch.

Personally, I just don't think I could sleep inside a bivy. I'm aware of all the benefits... but I think I'll stick with SpinnShelter alone for now. Plus that Nano bivy costs a small fortune anyway!!!!!!! Ouch!

Can a MYOG person do this without Cuben Material and stay at or very near the 7.5oz weight, cheap, maybe.

This morning I did another "what-if" and downsized the Alphamid Nano Tarp some more. I did the math for a smaller size. This one would be 3' wide by 7' across the front and back. It would also drop from 5.5' high to 5' high. The sq yards necessary for this size is (+/-) 6.18 sq yards. If I person could find some "true" 1oz or less weight waterproof spinnaker material a lot cheaper than say Cuben or other true 1oz stuff like SpinnTex that all cost in the $17 a yard range, you could still be at or under the 7.5oz mark of the Al..Nano Tarp BMW mentioned. You do have to be willing to go with a smaller footprint for this size.

I also took a look at the Stealth 1 NANO 7'x9' tarp. It is $170 and has about 7 yards of fabric in it. This comes out to about $24 a sq yard and change. I have no reason to think this number means anything but those numbers would make an Alphamid NANO tarp at 6 to 10 sq yards cost $24 to $30 times the sq yards of the Alphmid or a total possible cost in the $160 to $240 range.

I have spent more than $24 an ounce to save an ounce before.

I am going to dig out all my "never used" so called 0.50 spinnaker material and re-weigh it. If any of it is near a true 1oz per sq yard I might try a smaller Alphmid Tarp out of some. If not then I add another project to my Cuben list.

The pole length is 4.5' and the length of the tarp is just over 7'. These dimensions were scaled using the height of the Ti windscreen as my baseline. Ryan wouldn't cut down the windscreen to save a gram, would he?

Additionally I'm convinced this tarp doesn't have a rectangular footprint like the alphamid.

Goals/Desires?1. Big enough but no bigger than necessary.2. Very light, 7.5 ounce range, or less which should be light enough to get the attention of all us gram counters.3. Cost not a big problem but if a material that is cheaper than Cuben can be used go for it.

What do we think we know about the Alphamid Nano Tarp:

4. Made by Oware and modeled after their small Alphamid Tarp.5. Oware's small size is 4.5' x 9' x 5.5'.6. Alphamid Nano Tarp color seems to be gray to transparent. Cuben/Nano material is transparent and the gray looking color could be from the background.7. Size based on Roberts windscreen baseline idea seems to be just over 7' long and 4.5' high. Robert believes the tarp is not rectangular. I think the tarp is rectangular but maybe staked out in a way to distort the shape for a bit more room or to lift the edges to help vent the tarp when the front is closed.

Going with another size (3' x 7' and 4.5' high) I come up with about 5.63 sq yards of material to make the Alphamid Tarp. Again this does not add material for seams etc and someone can re-check my math.

A 3' x 7' footprint is big enough for me and is the same size as the small winter tent I made a few years ago. My tent was 5' high but 4' would have been high enough to sit-up in.

Using Cuben fiber and making the tarp this smaller size, 5.63 sq yards, and using the 0.35 to 0.44 oz a sq yard product, the finished weight could be in the (sit down) 3oz range (+/-) 0.5oz. The Cuben material at about $17 a yard would come out to $102 plus change. Add to this guy lines, stakes etc.

My next thought is I wonder how one of these would work on an AT Thru-Hike. It sure would be light and also be more private than a regular tarp.Even made out of some of the very cheap spinnaker material available this size might still weigh less than 7.5oz.